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Quadrajet Replacement and HEI Options

Entropy

Entropy

1971 K5 Blazer w/350
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Hi all,

I'm at the point in my life now where I'm tired of dealing with my finicky Quadrajet as well as the original points distributor.

For the carb, it's still the factory original but has been rebuilt at least 4 times since my Dad originally bought it new. It's time for another rebuild but honestly, the rebuilds I've had done up to this point (2 since I acquired it from my Dad), haven't resulted in smooth and consistent performance. I seem to have to spend a lot of time trying to tweak it, so I'm seriously considering just replacing it with something that's more reliable rather than another rebuild. I'm willing to consider anything from another carb to some kind of EFI system.

Altitude may also be part of the problem - I currently live at 7200 feet and spend a lot of time between 5200 and 10k feet in altitude. But I had a lot of these issues when I lived in Florida, Ohio, and Texas, so I don't think it's just the altitude.

Reading around it seems the issues I have with the QJ are pretty common and the key is to find someone who knows how to rebuild them. Are there any such people still around?

For the ignition system, it's all original, but I'd like to get away from points for less tweaking and maintenance and go with some kind of HEI system. Are there any recommended products/solutions that work particularly well in a 1st gen 350?

Thanks!

Andy
 
Can't go wrong with switching to fuel injection of some sort, but cost may be a factor. I did an LS swap myself and couldn't be happier.

afa HEI goes, it's stupid simple to change it out and way better. Check out this video:
 
ashman said:
Can't go wrong with switching to fuel injection of some sort, but cost may be a factor. I did an LS swap myself and couldn't be happier.

afa HEI goes, it's stupid simple to change it out and way better. Check out this video:
Click to expand...
Thanks, that's a great video.

Yeah, EFI looks pricey from my initial research. I Will likely stick with a carb for now and consider EFI or an LS swap at some point in the future, but that needs to wait until I get the bodywork sorted, which is turning out to be more challenging than I expected.
 
Meh on EFI, it’s super expensive. Get and hei distributor do that conversion, get an edelbrock AVS carb and be done with it.

I considered doing the edelbrock proflo swap and it’s just too much $$ for the amount of driving my K5 gets. A carb works for me, I don’t mind stomping my gas pedal an untold amount of time on a cold start.
 
TJ1978 said:
Meh on EFI, it’s super expensive. Get and hei distributor do that conversion, get an edelbrock AVS carb and be done with it.

I considered doing the edelbrock proflo swap and it’s just too much $$ for the amount of driving my K5 gets. A carb works for me, I don’t mind stomping my gas pedal an untold amount of time on a cold start.
Click to expand...
Thanks. I think that's my plan now. I hadn't heard of the AVS before (I haven't researched a carb replacement in almost a decade) so it sounds like just the thing I was looking for.
 
You will want to check the intake manifold you have. If it’s factory, you will need to change the intake to swap to something like a Holley carb due to the bolt pattern
 
I think a Holley Truck Avenger might be a bit more 4x4 friendly if your rig sees any off road action. The AVS is cool and all, but is meant to be a stock replacement for old Mopars and such. Both are square bore, so you'll need some sort of adaptor for it to work on your stock spread bore intake, or upgrade the intake at the same time. Depends on your budget I guess.
 
tRustyK5 said:
I think a Holley Truck Avenger might be a bit more 4x4 friendly if your rig sees any off road action. The AVS is cool and all, but is meant to be a stock replacement for old Mopars and such. Both are square bore, so you'll need some sort of adaptor for it to work on your stock spread bore intake, or upgrade the intake at the same time. Depends on your budget I guess.
Click to expand...
The intake is stock (and original), it probably does make sense to get a compatible intake rather than use an adapter. There are so many intake options, it's giving me some decision fatigue.

I'll check out the Holley Truck Avenger. I did discover in my research on the AVS that there is an "offroad" version which is supposed to be truck-friendly.

Thanks!
 
I know quadrajets fairly well, if you replaced yours with a commercial rebuild it's probably no good. Any rebuilder that removes the bronze colored coating from a carburator doen't know what they are doing, and just ruined that carb for ever more. Pass them by. 1 mistake that is common people tend to over tighten the front two bolts this warps and distorts the carb, causing all kinds of issues. Hopefully your replacement is decent. I would do the HEI conversion then see how thing go. 7200 feet, i am guessing you could leave the choke off except on the coldest mornings. Most common main jet for 350 Qjet is .69 with 37B rods and who knows what primary rod spring. For yours if not already I would 67 jets leave the rods alone, use the blue spring in the metering rod piston. maybe lower float level. I found mine wasn't getting enough fuel no matter what mechanical pump I used, I finally went electric with a return to tank, dead heading the electric pumps caused them to over heat and die.
 
Entropy said:
The intake is stock (and original), it probably does make sense to get a compatible intake rather than use an adapter. There are so many intake options, it's giving me some decision fatigue.

I'll check out the Holley Truck Avenger. I did discover in my research on the AVS that there is an "offroad" version which is supposed to be truck-friendly.

Thanks!
Click to expand...

Intake choices...I would suggest a dual plane for the best low end. Single plane will make more power at the top of the range, but at the expense of the low end power/response. For a mild small block, I'd consider the RPM Air Gap from Edelbrock.

 
@Entropy

if what @Wes Harden listed above isn’t lean enough, let me know. I have a spreadsheet with all the rod sizes and jets to get those down

for the back side, I liked the AN or DP rod on a G hanger

I’m at 5000’
 
Wes Harden said:

this bad boy will bolt on to your manifold. will be jetted way to rich for your alt. what style choke do have now? manual or divorced ?
Click to expand...

That may be a replacement for a Q-jet, but it will not perform as well as a Q-jet off road IMO. Holley made the Truck avenger for a reason...
 
Maybe, I was just looking for spread bores. there are off road floats and springs to keep them from bouncing. I mean you want perfect off roady you might as well go CNG or Propane. Even efi can get the fuel pump pickup uncovered.
 
Bent77 said:
@Entropy

if what @Wes Harden listed above isn’t lean enough, let me know. I have a spreadsheet with all the rod sizes and jets to get those down

for the back side, I liked the AN or DP rod on a G hanger

I’m at 5000’
Click to expand...
I think I was running a 62 or 63 equivalent. That’s what it would be jet only. I used that as a reference just to mix and match the rods/jets
 
Wes Harden said:
Maybe, I was just looking for spread bores. there are off road floats and springs to keep them from bouncing. I mean you want perfect off roady you might as well go CNG or Propane. Even efi can get the fuel pump pickup uncovered.
Click to expand...
They can. Filling the tank before going off road eliminates most of that. On the pickups, you need to use a Burb or Blazer tank. The hot dog shaped tanks most certainly will expose the pickup with not much effort
 
never realy paid attention to the truck avenger, came out long after I quit fooling with hollies. I do like the adjustable floats would get it just for that reason, or put those bowls on the spread bore of my choice. Vent tube can be made or modded. I'm sure the float are special but nothing that can't be adapted.
 
Yeah if you are going 62 63 jet you will have to change rods I don't think the original rod will fit those jets. I only have experience taking a high alt carb, making it work below 4000. Hopefully yours is close.

i have used this company and had good service. Bought parts only. https://quadrajetparts.com/
 
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